Like a bullet wrapped in a full metal jacket, a high-velocity hydrogen cloud hurtling toward the Milky Way appears to be encased in a shell of dark matter. stronomers believe that without this protective shell, the high-velocity cloud (HVC) known as the Smith Cloud would have disintegrated long ago when it first collided with the disk of our Galaxy.

A team of astronomers have identified what is believed to be the sibling of our sun – a star thought to have been born from the same cloud of gas at the one that provides our solar system with light and warmth.

On 24 October 2012 observatories across the world were alerted about a huge stellar explosion, the GRB121024A, which had been located just hours before in the Eridanus constellation by NASA's Swift satellite.

The prominent feature that allows for the existence of life on Earth is the Sun. Radiation from our closest star provides heat and energy to our planet, driving biological processes and providing the necessary conditions for liquid water to naturally exist.
But our Sun is only but one star in this vast Universe. And as it turns out, most stars are quite different than the one that illuminates our day. For this reason, scientists have, for hundreds of years, attempted to study the other...

Hertzsprung-Russell Diagram -- In stellar astronomy, the Hertzsprung-Russell diagram (H-R diagram) shows the relation between the absolute magnitude and the spectral types of stars. It was invented around 1910 by Ejnar Hertzsprung and Henry Norris Russell.
There are two equivalent forms. One is the observer's form which plots the color of the star on one axis and the absolute magnitude on the other axis.
The theoretician's form plots the temperature of the star on one axis and the...

Stellar Evolution -- Stellar evolution is the process of formation, life, and death of stars. It is one of the major topics of cosmogony.
Star Birth and Life
A star starts out as an enormous cloud of gas and dust many light-years across. Star formation begins when the cloud begins to condense under its own gravity. The processes that initiate this contraction are not fully understood. The cloud fragments fuse into stellar mass clouds known as protostars. Protostars do not emit...

Star Formation -- Star formation is the process by which gas in molecular clouds gets transformed into stars.
In the current paradigm of star formation, cores of molecular clouds (regions of specially high density) became gravitationally unstable, and start to concentrate.
Part of the gravitational energy lost in the process is radiated in the infrared, another part increases the temperature of the core. The accretion of material happen partially though a circumstellar disc.
When...

Star Designation -- The International Astronomical Union (IAU) is the internationally recognised authority for assigning designations to stars (and other celestial bodies).
Many of the star names in use today were inherited from the time before the IAU existed. Other names, mainly for variable stars (including novae and supernovae), are being added all the time.
Most stars, however, have no name and are referred to, if at all, by means of catalogue numbers. This article briefly...